The long range objectives for this project are to better understand the mechanism of ligand binding in heme proteins using ruthenium porphyrins and ruthenium substituted myoglobin and hemoglobin as model systems for the naturally occurring proteins. A broad understanding of oxygen binding in hemoglobin will provide information to better deal with genetic diseases involving hemoglobin. The specific aims of the project are two fold. First, the ligand exchange kinetics, electrochemistry, and spectroscopy of a series of ruthenium(II) porphyrins will be studied in order to determine the mode of bonding of ligands to ruthenium porphyrins. This is important to an understanding of how these ruthenium porphyrins function when incorporated into hemoglobin. Second, a series of ruthenium substituted heme proteins will be prepared and their CO and O2 affinities studied in order to learn more about the mechanism of ligand binding in native hemoglobin.